Cancel my contract

Dear O2,

On August 20, I wanted to order a Home L mobile internet at your store in Feuerbach. I mentioned to your colleague (we spoke in english) several times that I am interested in mobile internet, not DSL, and I asked him several times about it. He said of course, so I signed the contract. Unfortunately, I was there half an hour before closing time, so I realized that he had made a bad contract for me only after I was already on my way back to the accommodation and received the email about the contract. On the 23rd, I went back again to correct the error (misunderstanding), where he told me that unfortunately such a service cannot be established, only DSL, which he did not mention to me on the 20th, because then i would not order nothing.
Then I told him that I would like to cancel the contract then. He mentioned that we could try the 5G mobilnet, and made a phone call to the center. DSL was canceled (theoretically), so I signed the new contract for Home L. Another your colleague told me to wait 10 minutes because there is a little problem, then after the 10 minutes, he told me that both contracts were canceled and I had nothing more to do. I said goodbye and thought that was the end of the matter. Last week I was on vacation at home and I got back to the accommodation to find that the DSL router had been mailed out. I have two questions about this. If your colleague said that all contracts have been cancelled, why did you post the router? How can I return and cancel the contract permanently, because I have no intention and it is not possible to install DSL in my accommodation.
Thank you in advance for your reply,

Sincerely, Norbert